Читать книгу An Illustrated Guide to Oral Histology - Группа авторов - Страница 32

The tooth root has many important functions including anchorage of the tooth in maxilla/mandible and facilitating provision of blood supply (through apical foramina). The inside of the root is composed of radicular dentin and pulp canals whereas, on the outside, it is covered by a thin calcified layer of cementum. Root formation occurs because of the interaction between HERS, dental papilla, and dental follicle. After crown formation, the cervical loop grows apically as HERS circling dental papilla. The ectomesenchymal cells of dental papilla near the HERS change into odontoblasts and start secreting radicular dentin. The root dentin comes in contact with the dental follicle due to the perforation of HERS which leads to its mesh‐network appearance. This contact changes dental follicular cells into cementoblasts (forming cementum), fibroblasts (forming PDL), and osteoblasts (forming alveolar bone). It should be noted that the HERS only maps the shape of the root and then disintegrates. Its remnants are known as epithelial cell rests of Malassez.